Effect of substrate and fermentation conditions on pectinase and cellulase production by Aspergillus niger NCIM 548 in submerged (SmF) and solid state fermentation (SSF)

Optimised Degradation of Lignocelluloses by Edible Filamentous Fungi for the Efficient Biorefinery of Sugar Beet Pulp

The degradation of the complex structure of lignocellulosic biomass is important for its further biorefinery to value-added bioproducts. The use of effective fungal species for the optimised degradation of biomass can promote the effectiveness of the biorefinery of such raw material. In this study, the optimisation of processing parameters (temperature, time, and s/w ratio) for cellulase activity and reducing sugar (RS) production through the hydrolysis of sugar beet pulp (SBP) by edible filamentous fungi of Aspergillus, Fusarium, Botrytis, Penicillium, Rhizopus, and Verticillium spp. was performed. The production of RS was analysed at various solid/water (s/w) ratios (1:10-1:20), different incubation temperatures (20-35 °C), and processing times (60-168 h). The Aspergillus niger CCF 3264 and Penicillium oxalicum CCF 3438 strains showed the most effective carboxymethyl cellulose (CMC) degrading activity and also sugar recovery (15.9-44.8%) from SBP biomass in the one-factor experiments. Mathematical data evaluation indicated that the highest RS concentration (39.15 g/100 g d.w.) and cellulolytic activity (6.67 U/g d.w.) could be achieved using A. niger CCF 3264 for the degradation of SBP at 26 °C temperature with 136 h of processing time and a 1:15 solid/water ratio. This study demonstrates the potential of fungal degradation to be used for SBP biorefining.

Biosynthesis of silver nanoparticles using nitrate reductase from Aspergillus terreus N4 and their potential use as a non-alcoholic disinfectant

Green technology has been developed for the quick production of stabilized silver nanoparticles (AgNPs), with the assistance of nitrate reductase from an isolated culture of Aspergillus terreus N4. The organism's intracellular and periplasmic fractions contained nitrate reductase, with the former demonstrating the highest activity of 0.20 IU/g of mycelium. When the fungus was cultivated in a medium comprising 1.056% glucose, 1.836% peptone, 0.3386% yeast extract, and 0.025% KNO3, the greatest nitrate reductase productivity of 0.3268 IU/g was achieved. Statistical modeling via response surface methodology was used to optimize the enzyme production. The periplasmic and intracellular enzyme fractions were found to convert Ag+ to Ag0, initiating synthesis within 20 min, with predominant nanoparticle sizes between 25 and 30 nm. By normalizing the effects of temperature, pH, AgNO3 concentration, and mycelium age with a variable shaking period for enzyme release, the production of AgNPs with the periplasmic fraction was optimized. The synthesis of nanoparticles occurred at temperatures of 30, 40, and 50 °C, with the highest yield observed at 40 and 50 °C during shorter incubation periods. Similarly, the nanoparticles were synthesized at pH levels of 7.0, 8.0, and 9.0, with the greatest production observed at pH 8.0 and 9.0 at lower incubation periods. The antimicrobial activity of AgNPs was demonstrated against common foodborne pathogens, including Staphylococcus aureus and Salmonella typhimurium, indicating their potential as non-alcoholic disinfectants.

Exo-polygalacturonase production enhancement by Piriformospora indica from sugar beet pulp under submerged fermentation using the response surface methodology

This study proposed a novel and cost-effective approach to enhance and optimize the exo-polygalacturonase from P. indica, a root endophytic fungus. In the current investigation, the impact of ammonium sulfate, sugar beet pulp (SBP), and glucose as variables on induction of exo-polygalacturonase from P. indica was optimized using the central composite design (CCD) of response surface methodology (RSM) under submerged fermentation (SmF). Additionally, determination of the exo-polygalacturonase molecular weight and in situ analysis was performed. The optimal reaction conditions, which resulted in the highest enzyme activity, were observed in the following conditions: ammonium sulfate (4 g/L), SBP (20 g/L), and glucose (60 g/L). Under the optimized condition, the maximum enzyme activity reached 19.4 U/ml (127 U/mg), which increased by 5.84 times compared to non-optimized conditions. The exo-polygalacturonase molecular weight was estimated at 60 KDa. In line with the bioinformatic analysis, the exo-polygalacturonase sequence of P. indica showed similarity with Rhizoctonia solani's and Thanateporus cucumeris. These results indicated that SBP acts as a cheap and suitable inducer of exo-polygalacturonase production by P. indica in submerged cultivation. The outcome of this study will be useful for industries to decrease environmental pollution with cost-effective approaches.

Advanced strategies for production of soy-processing enzyme

Enzyme production is critical and often costly for biorefinery. It is challenging to produce enzymes with not only high titers but also proper combinations of all required activities in a single fermentation. This work aimed at improving productivity and composition of the multiple enzyme activities required for hydrolysis of complex soybean carbohydrate in a single fermentation. A previously selected Aspergillus niger strain was used for its high carbohydrases and low protease production. Strategies of fed-batch substrate addition and programmed pH-decrease rates were evaluated. Cheap soybean hull (SH) was confirmed to induce production of all necessary carbohydrases. Surprisingly, fed-batch SH addition, originally thought to sustain substrate-inducer availability and reduce feedback repression by sugars, did not increase pectinase and cellulase production significantly and even lowered the α-galactosidase production, when compared with batch fermentation having the same total SH amount (all added initially). On the other hand, the pH-decrease rate could be effectively optimized for production of complex enzyme mixtures. The best fermentation was programmed to lower pH from 7 to 4 in 84 h, at a drop rate of .0357 per h. It produced the highest pectinase (19.1 ± .04 U/mL), α-galactosidase (15.7 ± .4 U/mL), and cellulase (.88 ± .06 FPU/mL). Producing these high enzyme activities in a single fermentation significantly improves the effectiveness and economics of enzymatic soy processing, which, e.g., can hydrolyze the 30%-35% carbohydrate in soybean meal to sugars, with minimal protein degradation, to generate high-value protein-rich products and a hydrolysate as fermentation feedstock.

Evaluation of wool protein hydrolysate as peptone for production of microbial enzymes

Peptones are one of the most expensive components of microbial culture media. The present study was conducted to test the usability of low-cost sheep wool peptone (SWP) as an organic nitrogen source in the production of six industrially important enzymes (lipase, amylase, tannase, pectinase, cellulase and invertase). SWP was prepared by alkaline hydrolysis and acid neutralization. Bacillus licheniformis and Aspergillus niger were selected as test microorganisms for enzyme production. To evaluate the efficacy of SWP in enzyme production, it was compared with commercial tryptone peptone (TP) in the shaking flask cultures of the test microorganisms. The optimum concentration of both SWP and TP was determined to be 8 g/L for the production of B. licheniformis-derived enzymes, but 6 g/L for the production of A. niger-derived enzymes. It was determined that SWP was superior to TP in the production of four enzymes (lipase, amylase, tannase and pectinase) of both B. licheniformis and A. niger. This is the first study about the usage of sheep wool protein hydrolysate (SWP) as an organic nitrogen source or a peptone in fermentative production of microbial enzymes.

Response-Surface Statistical Optimization of Submerged Fermentation for Pectinase and Cellulase Production by Mucor circinelloides and M. hiemalis

Cellulase and pectinase are degrading cellulosic and pectic substances that form plant cell walls and, thereby, they have a wide range of applications in the agro-industrial by-products recycling and food industries. In the current research, Mucor circinelloides and M. hiemalis strains were tested for their ability to produce cellulase and pectinase from tangerine peel by submerged fermentation. Experiments on five variables: temperature, pH, incubation period, inoculum size, and substrate concentration, were designed with a Box–Behnken design, as well as response surface methodology (RSM), and analysis of variance was performed. In addition, cellulase and pectinase were partially purified and characterized. At their optimum parameters, M. circinelloides and M. hiemalis afforded high cellulase production (37.20 U/mL and 33.82 U/mL, respectively) and pectinase (38.02 U/mL and 39.76 U/mL, respectively). The partial purification of M. circinelloides and M. hiemalis cellulase produced 1.73- and 2.03-fold purification with 31.12 and 32.02% recovery, respectively; meanwhile, 1.74- and 1.99-fold purification with 31.26 and 31.51% recovery, respectively, were obtained for pectinase. Partially purified cellulase and pectinase from M. circinelloides and M. hiemalis demonstrated the highest activity at neutral pH, and 70 and 50 °C, for cellulase and 50 and 60 °C, for pectinase, respectively. Moreover, 10 mM of K+ increased M. circinelloides enzymatic activity. The production of cellulase and pectinase from M. circinelloides and M. hiemalis utilizing RSM is deemed profitable for the decomposition of agro-industrial wastes.

A Novel Endo-Polygalacturonase from Penicillium oxalicum: Gene Cloning, Heterologous Expression and Its Use in Acidic Fruit Juice Extraction

An endo-polygalacturonase (endo-PGase) exhibiting excellent performance during acidic fruit juice production would be highly attractive to the fruit juice industry. However, candidate endo-PGases for this purpose have rarely been reported. In this study, we expressed a gene from Penicillium oxalicum in Pichia pastoris. The recombinant enzyme PoxaEnPG28C had an optimal enzyme activity at pH 4.5 and 45°C and was stable at pH 3.0-6.5 and < 45°C. The enzyme had a specific activity of 4,377.65 ± 55.37 U/mg towards polygalacturonic acid, and the K_m and V_max values of PoxaEnPG28C were calculated as 1.64 g/l and 6127.45 U/mg, respectively. PoxaEnPG28C increased the light transmittance of orange, lemon, strawberry and hawthorn juice by 13.9 ± 0.3%, 29.4 ± 3.8%, 95.7 ± 10.2% and 79.8 ± 1.7%, respectively; it reduced the viscosity of the same juices by 25.7 ± 1.6%, 52.0 ± 4.5%, 48.2 ± 0.7% and 80.5 ± 2.3%, respectively, and it increased the yield of the juices by 24.5 ± 0.7%, 12.7 ± 2.2%, 48.5 ± 4.2% and 104.5 ± 6.4%, respectively. Thus, PoxaEnPG28C could be considered an excellent candidate enzyme for acidic fruit juice production. Remarkably, fruit juice production using hawthorn as an material was reported for the first time.

Optimization of the factors affecting BT-2 black tea fermentation by observing their combined effects on the quality parameters of made tea using Response Surface Methodology (RSM)

This research work aimed to optimize the fermentation time, temperature, and relative humidity of the black tea produced from Bangladesh Tea 2 (BT-2) variety by observing their quality parameters. Total theaflavin (TF), thearubigin (TR), the ratio of TF: TR, total liquor color (TLC), high polymeric substances (HPS), and total phenolic content (TPC) were evaluated for quality measurements of BT-2 black tea. Response Surface Methodology (RSM) with Box-Behnken design (BBD) was applied to optimize fermentation time, temperature, and relative humidity as well as evaluate the effects of optimized conditions on the quality of made tea. The results obtained from the response surface optimization affirmed that under the optimum conditions of time (80.14 min), temperature (28.76 °C), and relative humidity (92.30%), the model showed the value of TF (0.69%), TR (5.57%), HPS (8.61%), TLC (3.05%), and TPC (7.95 GAE g/100g tea). Moreover, the optimized model found that the TF:TR value was 1:9.13, which is close to black tea's optimum quality. The values observed in experiments were highly congruent with the predicted value by the regression model. The Analysis of Variance (ANOVA) test revealed that the model was significant for TF, TR, HPS, TLC, TPC, and TF:TR values of prepared BT-2 black tea at different levels (p < 0.001 to p < 0.01). The composite desirability of the model was 0.93, which suggests that the developed model could be utilized effectively to maintain the quality parameters of BT-2 black tea during fermentation.

Optimization of substrate composition for pectinase production from Satkara (Citrus macroptera) peel using Aspergillus niger-ATCC 1640 in solid-state fermentation

Pectinase is an enzyme having a broad industrial and commercial application. However, higher production costs may be the major constraint for the wide-scale application of pectinase. Therefore, researchers are trying to reduce the pectinase production cost for subsequent application in the industrial processes by using a unique substrate and optimizing the fermentation medium components and process conditions. The main purpose of the current study was to optimize medium composition for pectinase production using Aspergillus niger-ATCC 1640 in the solid-state fermentation. The Response Surface Methodology (RSM) was performed to evaluate the effects of variables, specifically the concentrations of Satkara peel, urea, (NH₄)₂PO₄, NH₄NO₃, KH₂PO₄, ZnSO₄, and MgSO₄.7H₂O on pectinase production in the solid substrate. Firstly, a two-factorial design, Plackett-Burman design (PBD) was applied to screen the variables that significantly influenced the pectinase production. After finding the critical variables, 15 experimental runs were carried out using a Box-Behnken design (BBD) to derive a statistical model for optimizing the concentrations of the selected variables. The PBD model revealed that Satkara peel, urea, and (NH₄)₂SO₄ significantly affected the pectinase production. RSM results indicated that the predicted response for pectinase production was in good agreement with experimental data (R² = 0.9836). Under the optimized condition of Satkara peel (8.4 g/L), urea (0.5 g/L), and (NH₄)₂SO4 (2.7 g/L), the pectinase activity was predicted to be 0.6178 μmol/mL. In the present study, the experimental pectinase production achieved 0.6045 μmol/mL. The study revealed that optimization through RSM could improve the pectinase production from Satkara peel.

Action of Extracellular Proteases of Aspergillus flavus and Aspergillus ochraceus Micromycetes on Plasma Hemostasis Proteins

In this study, we investigated the properties of proteolytic enzymes of two species of Aspergillus, Aspergillus flavus 1 (with a high degree of pathogenicity) and Aspergillus ochraceus L-1 (a conditional pathogen), and their effects on various components of the hemostasis system (in vitro) in the case of their penetration into the bloodstream. We showed that micromycete proteases were highly active in cleaving both globular (albuminolysis) and fibrillar (fibrin) proteins, and, to varying degrees, they could coagulate the plasma of humans and animals (due to proteolysis of factors of the blood coagulation cascade) but were not able to coagulate fibrinogen. The proteases of both Aspergillus fully hydrolyzed thrombi in 120-180 min. Micromycetes did not show hemolytic activity but were able to break down hemoglobin.

Feasibility of multi-hydrolytic enzymes production from optimized grape pomace residues and wheat bran mixture using Aspergillus niger in an integrated citric acid-enzymes production process

In this study, the potential of the co-generation of hydrolytic enzymes in the biorefinery plant for citric acid fermentation was investigated. Aspergillus niger B60 mycelium along with the solid residue after the recovery of sugars from white pomace (WP') were recycled from citric acid fermentation. A mixture design was used to determine the optimum ternary feedstock mixture composed of WP' (15%), red grape pomace (15%) and wheat bran (70%) that produced the target enzymes with high activities, which were compared to those from pure feedstocks. Maximum carboxymethyl cellulase, polygalacturonase, amylase, xylanase and acid protease activities obtained through solid-state fermentation (120 h, 30 °C) of the feedstock mixture were 668 IU/g, 3,151 IU/g, 1,099 IU/g, 579 IU/g and 204 IU/g (dry mass basis), respectively. The system was successfully simulated in SuperPro Designer. Results showed that the enzymes production process serves as the main contributor to the profitability of the biorefinery plant.

Black liquor: A potential moistening agent for production of cost-effective hydrolytic enzymes by a newly isolated cellulo-xylano fungal strain Aspergillus tubingensis and its role in higher saccharification efficiency

In the present study, black liquor generated during mild alkali pre-treatment was evaluated as a moistening agent to produce cost effective hydrolytic enzymes using novel cellulo-xylano fungal strain Aspergillus tubingensis M7. The fungus competently produced 21.90 and 22.46 filter paper, 1004 and 1369 endoglucanase, 117 and 142 β-glucosidase and 8188 and 7981 U/g xylanase activity by using modified Mandel & weber's and black liquor medium, respectively. The crude hydrolytic enzymes from black liquor were evaluated for saccharification of pre-treated biomass. Reducing sugar yields (mg/g substrate) and the corresponding saccharification efficiency (%) from rice straw, corncob, sugarcane bagasse and banana stem were 745.50 (86.02; 18 h); 596 (74.50; 24 h); 358.15 (42.98; 24 h) and 245.70 (33.00; 24 h), respectively. Residual biomass compositional analysis revealed that reduced onset temperature, increased activation energy and pre-exponential factor in saccharified biomass as compared to pre-treated and untreated biomass, suggesting their utilization for pyrolysis to obtain value added products.

Microbial synergy between Pichia kudriazevii YS201 and Bacillus subtilis BS38 improves pulp degradation and aroma production in cocoa pulp simulation medium

Interactions between two major microorganisms from Ivorian cocoa fermentation, namely Bacillus subtilis BS38 and Pichia kudriazevii YS201, were investigated during fermentation in cocoa pulp simulation medium. The strains were mutually inhibitory, with Bacillus being more susceptible to this antagonistic effect than Pichia. However, both strains yielded different pulp-degrading enzymes, namely polygalacturonase (PG) from Pichia and pectate lyase (Pel) from Bacillus, that cooperate to efficiently breakdown pectin and vegetable pulp. The quantification of aromas from microbial cultures using Gas Chromatography-Mass Spectroscopy (GC-MS) coupled with headspace microextration (SPME) method, showed that P. kudriazevii produce mainly alcohols such as ethanol (63.165 g/L), phenylethanol (1.005 g/L), methylbutanol (0.138 g/L) and esters, notably ethyl acetate (0.037 g/L) and isoamyl acetate (0.032 g/L). The volatile fraction produced by Bacillus was dominated by butanediol (5.707 g/L), acetoin (1.933 g/L), phenylethanol (0.035 g/L) and acetic acid (0.034 g/L). In co-culture, Bacillus produced low levels of aroma compounds whereas a moderate decrease in the production of these compounds was observed in the yeasts strain. Thus, the dominant aromas present in the co-culture were mainly those from the yeasts strain; however, a 1.37 fold increase of ethanol production was observed in co-culture indicating a synergy between the strains. This study showed that cooperation between B. subtilis BS38 and P. kudriazevii YS201 leads principally to increasing pulp degradation and ethanol production, known as desirable properties for a well processing of cocoa fermentation.

Functional metabolomics approach reveals the reduced biosynthesis of fatty acids and TCA cycle is required for pectinase activity in Bacillus licheniformis

Increase of pectinase activity is especially important in fermentation industry. Understanding of the metabolic mechanisms can find metabolic modulation approach to promote high yield of pectinase. Higher activity of pectinase was detected in DY1 than DY2, two strains of Bacillus licheniformis. GC-MS-based metabolomics identified differential metabolome of DY2 compared with DY1, characterizing the increased TCA cycle and biosynthesis of fatty acids. Elevated activity of pyruvate dehydrogenase (PDH), α-ketoglutaric dehydrogenase (KGDH) and succinate dehydrogenase (SDH) showed global elevation of carbon metabolism, which is consistent with the result that lowers glucose in DY2 than DY1. Inhibitors malonate, furfural and triclosan, of PDH, SDH and biosynthesis of fatty acids, promoted pectinase activity, where triclosan increased pectinase activity by 179%. These results indicate that functional metabolomics is an effective approach to understand metabolic mechanisms of fermentation production and provides clues to develop new methods for changing bacterial physiology and production.

Microparticle-enhanced polygalacturonase production by wild type Aspergillus sojae

Polygalacturonases (PGs), an important industrial enzyme group classified under depolymerases, catalyze the hydrolytic cleavage of the polygalacturonic acid chain through the introduction of water across the oxygen bridge. In order to produce and increase the concentration of this enzyme group in fermentation processes, a new approach called microparticle cultivation, a promising and remarkable method, has been used. The aim of this study was to increase the PG activity of Aspergillus sojae using aluminum oxide (Al₂O₃) as microparticles in shake flask fermentation medium. Results indicated that the highest PG activity of 34.55 ± 0.5 U/ml was achieved with the addition of 20 g/L of Al₂O₃ while the lowest activity of 15.20 ± 0.2 U/mL was obtained in the presence of 0.1 g/L of Al₂O₃. In fermentation without microparticles as control, the activity was 15.64 ± 3.3 U/mL. Results showed that the maximum PG activity was 2.2-fold higher than control. Additionally, smaller pellets formed with the addition of Al₂O₃ where the lowest pellet diameter was 955.1 µm when 10 g/L of the microparticle was used. Also, it was noticed that biomass concentration gradually increased with increasing microparticle concentration in the fermentation media. Consequently, the PG activity was significantly increased in microparticle-enhanced shake flask fermentation. In fact, these promising preliminary data can be of significance to improve the enzyme activity in large-scale bioreactors.

Lignocellulose degradation patterns, structural changes, and enzyme secretion by Inonotus obliquus on straw biomass under submerged fermentation

This study examined the white rot fungus I. obliquus on the degradation of three types of straw biomass and the production of extracellular lignocellulolytic enzymes under submerged fermentation. The fungus process resulted in a highest lignin loss of 72%, 39%, and 47% in wheat straw, rice straw, and corn stover within 12days, respectively. In merely two days, the fungus selectively degraded wheat straw lignin by 37%, with only limited cellulose degradation (13%). Fourier transform infrared spectroscopy revealed that the fungus most effectively degraded the wheat straw lignin and rice straw crystalline cellulose. Scanning electronic microscopy showed the most pronounced structural changes in wheat straw. High activities of manganese peroxidase (159.0U/mL) and lignin peroxidase (123.4U/mL) were observed in wheat straw culture on Day 2 and 4, respectively. Rice straw was the best substrate to induce the production of cellulase and xylanase.

Extracellular Xylanopectinolytic Enzymes by Bacillus subtilis ADI1 from EFB's Compost

Microbial xylanase and pectinase are two extremely valuable enzymes, which have captivated much attention. This can be seen from the increased demand for these enzymes by many industrial sectors. This study investigates the isolation and screening of extracellular xylanopectinolytic enzymes-producing bacteria in a submerged fermentation (SmF). Samples are collected from the compost of empty fruit bunch (EFB) at Biocompost Pilot Plant, located at Biorefinery Plant, Universiti Putra Malaysia. From the experiment, out of 20 isolates, 11 isolates show xylanase or/and pectinase activity, and only one isolate (EFB-11) shows the concurrent activities of xylanase and pectinase. These activities are selected for enzyme production under submerged fermentation (quantitative screening). At the 72nd hour of incubation, xylanase and pectinase show the highest production, which ranges about 42.33 U/mL and 62.17 U/mL (with low amount of cellulase present), supplemented with 2% (w/v) of rice bran as carbon source at incubation temperature level, which is 30°C. Meanwhile, the pH of media is shifted to 8.42, which indicates that EFB-11 isolate is alkalotolerant bacteria and identified as Bacillus subtilis ADI1. This strain proves to have potential in agroindustrial bioconversion and has a promising ability to scale up to an industrial scale.

Cellulase production using natural medium and its application on enzymatic hydrolysis of thermo chemically pretreated biomass

Lignocellulosic bioethanol is an important renewable fuel for transportation purpose. Commercial production of lignocellulosic bioethanol mainly depends on cost of cellulase production, efficient pretreatment and enzymatic hydrolysis process. In the present study cellulase production from Aspergillus niger under submerged fermentation (SmF) was optimized using coconut water as natural medium. Maximum cellulase production (0.53 IU/mL) was achieved within 3 days of incubation using 8 % (w/v) waste paper and 0.07 % (w/v) glucose. The produced cellulase was applied for enzymatic hydrolysis of thermo chemically (dilute acid and alkaline) pretreated biomass (equal mixture of wheat straw and cotton stalk). Optimization of dilute acid and dilute alkaline pretreatment showed dilute alkaline pretreatment was more effective for higher reducing sugar production. Maximum reducing sugar yield of 398.0 mg/g dry biomass was obtained from dilute alkaline pretreated biomass (using 0.5 M sodium hydroxide, 8 % substrate concentration, 120 °C temperature and 20 min of incubation time). The presence of difference sugars (glucose, xylose, mannose, maltose) in the saccharified sample was confirmed by thin layer chromatographic analysis. The effectiveness of dilute alkaline pretreatment was further confirmed by biochemical composition (cellulose, hemicelluloses and lignin) and structural (furrier transformed infrared spectroscopic and scanning electron microscopic) analysis. The above result can be useful for commercial production of lignocellulosic bioethanol.

Effect of passive transport of water through plasma membrane in production of extracellular enzyme

In this article, availability and control of water in solid-state fermentation (SSF) were investigated. Based on passive transport of water through plasma membranes, a new model was proposed for calculation and control of water activities in the mixture of solids. The validity of theoretical model and accuracy of the proposed model were proved by experimental data. This model was used for production of pectinases via mixed-SSF with the aid of a rotary drum bioreactor. It was found that in case of extracellular enzyme production, the new model is in good agreement with experimental data for the control of water activities in the mixed-SSF. Exact control of water activity in SFF, the production of endo- and exo-pectinases was relatively enhanced. Based on theoretical view point, the prominence of this new model in control of water activity was also proved.

Modelling of different enzyme productions by solid-state fermentation on several agro-industrial residues

A simple kinetic model, with only three fitting parameters, for several enzyme productions in Petri dishes by solid-state fermentation is proposed in this paper, which may be a valuable tool for simulation of this type of processes. Basically, the model is able to predict temporal fungal enzyme production by solid-state fermentation on complex substrates, maximum enzyme activity expected and time at which these maxima are reached. In this work, several fermentations in solid state were performed in Petri dishes, using four filamentous fungi grown on different agro-industrial residues, measuring xylanase, exo-polygalacturonase, cellulose and laccase activities over time. Regression coefficients after fitting experimental data to the proposed model turned out to be quite high in all cases. In fact, these results are very interesting considering, on the one hand, the simplicity of the model and, on the other hand, that enzyme activities correspond to different enzymes, produced by different fungi on different substrates.

Effect of pH, Temperature, and Chemicals on the Endoglucanases and β-Glucosidases from the Thermophilic Fungus Myceliophthora heterothallica F.2.1.4. Obtained by Solid-State and Submerged Cultivation

This work reports endoglucanase and beta-glucosidase production by the thermophilic fungus Myceliophthora heterothallica in solid-state (SSC) and submerged (SmC) cultivation. Wheat bran and sugarcane bagasse were used for SSC and cardboard for SmC. Highest endoglucanase production in SSC occurred after 192 hours: 1,170.6 ± 0.8 U/g, and in SmC after 168 hours: 2,642 ± 561 U/g. The endoglucanases and beta-glucosidases produced by both cultivation systems showed slight differences concerning their optimal pH and temperature. The number of endoglucanases was also different: six isoforms in SSC and ten in SmC. Endoglucanase activity remained above 50% after incubation between pH 3.0 and 9.0 for 24 h for both cultivation systems. The effect of several chemicals displayed variation between SSC and SmC isoenzymes. Manganese activated the enzymes from SmC but inhibited those from SSC. For β-glucosidases, maximum production on SmC was 244 ± 48 U/g after 168 hours using cardboard as carbon source. In SSC maximum production reached 10.9 ± 0.3 U/g after 240 h with 1 : 1 wheat bran and sugarcane bagasse. Manganese exerted a significant activation on SSC β-glucosidases, and glucose inhibited the enzymes from both cultivation systems. FeCl3 exerted the strongest inhibition for endoglucanases and β-glucosidases.

Fermentation Optimization and Unstructured Kinetic Model for Cellulase Production by Rhizopus stolonifer var. reflexus TP-02 on Agriculture By-Products

Agricultural by-products, rice straw, wheat bran juice, and soybean residue, were used as substrates for cellulase production using Rhizopus stolonifer var. reflexus TP-02. The culture medium was optimized though uniform design experimentation during shaking flask fermentation, and the ideal formulation obtained for filter paper enzyme (FPase) production was 10 % bran diffusion juice, 1 % rice straw, 0.17 % urea, 0.17 % soybean residue, 0.11 % KH2PO4, and 0.027 % Tween 80, and the maximal FPase activity in the culture supernatant was 13.16 U/mL at an incubation time of 3 days. A kinetic model for cellulase production in batch fermentation was subsequently developed. The unstructured kinetic model considered three responses, namely biomass, cellulase, and sugar. Models for the production of three types of cellulase components (i.e., endoglucanases, cellobiohydrolases, and β-glucosidases) were established to adequately describe the cellulase production pattern. It was found that the models fitted the experimental data well under pH 5.0 and 6.0, but only the avicelase production model predicted the experimental data under pH-uncontrolled conditions.

Comparative study of multi-enzyme production from typical agro-industrial residues and ultrasound-assisted extraction of crude enzyme in fermentation with Aspergillus japonicus PJ01

Submerged fermentation (SmF) and solid-state fermentation (SSF) of Aspergillus japonicus PJ01 for multi-enzyme complexes (MEC) production were comparatively studied. The results showed that orange peel and wheat bran were the best substrates for MEC production in SmF and SSF, respectively. After 72 h of cultivation under SmF, the maximal pectinase, CMCase, and xylanase activities reached 2610, 85, and 335 U/gds (units/gram dry substrate), respectively; while after 72 h of cultivation under SSF, these three enzymes' activities reached 966, 58, and 1004 U/gds, respectively. Effects of ultrasound on extraction of crude enzymes from SSF medium were determined, the maximal activities of pectinase, CMCase, and xylanase increased to 1.20, 1.48, and 1.30-fold, respectively. Apparent different mycelia growths of SSF and SmF were observed by scanning electron microscopy; and different isoforms of the crude enzyme extracts from SSF and SmF were presented by zymogram analysis.

Efficient polygalacturonase production from agricultural and agro-industrial residues by solid-state culture of Aspergillus sojae under optimized conditions

Previously identified fungal pectinase producers of the species Aspergillus sojae were used for optimization of polygalacturonase production in solid-state fermentation applying Design of Experiment. The effects of media composition and several process parameters, like inoculum size, moisture level, incubation time and temperature on polygalacturonase activity were studied in screening and optimization investigations. Utilization of agricultural and agro-industrial by-products provided the establishment of a cost-efficient and sustainable process for enzyme production. Comparison of pectinase production by A. sojae ATCC 20235 and A. sojae CBS 100928 under optimized conditions yielded 6.9 times higher polygalacturonase activity by A. sojae ATCC 20235. Highest enzyme yield (909.5 ± 2.7 U/g) was obtained by A. sojae ATCC 20235 after 8 days at 30°C applying 30% sugar beet pulp as inducer substrate in combination with wheat bran as medium wetted at 160% with 0.2 M HCl. Furthermore, an overview of pectinolytic enzyme activities present in the extracts of both strains is provided. Protein profiles of both strains are given by SDS-PAGE electrophoresis, as well as zymograms for pectinolytic enzymes in comparison to commercial pectinase preparations.

Comparative Effect of Crude and Commercial Enzyme on the Juice Recovery from Bael Fruit (Aegle marmelos Correa) Using Principal Component Analysis

The effect of incubation time, incubation temperature, and crude enzyme concentration was observed on the yield, viscosity, and clarity of the juice obtained from bael fruit pulp. The recommended enzymatic treatment conditions from the study were incubation time 475 min, incubation temperature 45°C, and crude enzyme concentration 0.20 mL/25 g bael fruit pulp. The recovery, viscosity, and clarity of the juice under these conditions were 82.9%, 1.41 cps, and 21.32%T, respectively. The variables, clarity, and yield were found as principal components for comparing different samples of the juice treated with enzyme.

Co-production of tannase and pectinase by free and immobilized cells of the yeast Rhodotorula glutinis MP-10 isolated from tannin-rich persimmon (Diospyros kaki L.) fruits

Hyper tannase and pectinase-producing yeast Rhodotorula glutinis MP-10 was isolated from persimmon (Diospyros kaki L.) fruits. The main pectinase activity of yeast was exo-polygalacturonase. No pectin methyl esterase and too low pectin lyase activities were detected for this yeast. The maximum exo-activities of tannase and polygalacturonase were determined as 15.2 and 26.9 U/mL for free cells and 19.8 and 28.6 U/mL for immobilized cells, respectively. Immobilized cells could be reused in 13 successive reaction cycles without any loss in the maximum tannase and polygalacturonase activities. Besides, too little decreases in activities of these enzymes were recorded between 14 and 18 cycles. At the end of 18 successive reaction cycles, total 503.1 U/mL of polygalacturonase and 349.6 U/mL of tannase could be produced using the same immobilized cells. This is the first report on the use of free and/or immobilized cells of a microorganism for the co-production of tannase and pectinase.